ObjectivesRoux-en-Y gastric bypass (RYGB) has greater efficacy for weight loss in obese patients than gastric banding (BAND) surgery. We hypothesise that this may result from different effects on food hedonics via physiological changes secondary to distinct gut anatomy manipulations.DesignWe used functional MRI, eating behaviour and hormonal phenotyping to compare body mass index (BMI)-matched unoperated controls and patients after RYGB and BAND surgery for obesity.ResultsObese patients after RYGB had lower brain-hedonic responses to food than patients after BAND surgery. RYGB patients had lower activation than BAND patients in brain reward systems, particularly to high-calorie foods, including the orbitofrontal cortex, amygdala, caudate nucleus, nucleus accumbens and hippocampus. This was associated with lower palatability and appeal of high-calorie foods and healthier eating behaviour, including less fat intake, in RYGB compared with BAND patients and/or BMI-matched unoperated controls. These differences were not explicable by differences in hunger or psychological traits between the surgical groups, but anorexigenic plasma gut hormones (GLP-1 and PYY), plasma bile acids and symptoms of dumping syndrome were increased in RYGB patients.ConclusionsThe identification of these differences in food hedonic responses as a result of altered gut anatomy/physiology provides a novel explanation for the more favourable long-term weight loss seen after RYGB than after BAND surgery, highlighting the importance of the gut–brain axis in the control of reward-based eating behaviour.

AimIncreased body iron is associated with insulin resistance. Hepcidin is the key hormone that negatively regulates iron homeostasis. We hypothesized that individuals with insulin resistance have inadequate hepcidin levels for their iron load.MethodsSerum concentrations of the active form of hepcidin (hepcidin-25) and hepcidin:ferritin ratio were evaluated in participants with Type 2 diabetes (n = 33, control subjects matched for age, gender and BMI,n = 33) and participants with polycystic ovary syndrome (n = 27, control subjects matched for age and BMI,n = 16). To investigate whether any changes observed were associated with insulin resistance rather than insulin deficiency or hyperglycaemia per se, the same measurements were made in participants with Type 1 diabetes (n = 28, control subjects matched for age, gender and BMI,n = 30). Finally, the relationship between homeostasis model assessment of insulin resistance and serum hepcidin:ferritin ratio was explored in overweight or obese participants without diabetes (n = 16).ResultsParticipants with Type 2 diabetes had significantly lower hepcidin and hepcidin:ferritin ratio than control subjects (P < 0.05 and P < 0.01, respectively). Participants with polycystic ovary syndrome had a significantly lower hepcidin:ferritin ratio than control subjects (P < 0.05). There was no significant difference in hepcidin or hepcidin:ferritin ratio between participants with Type 1 diabetes and control subjects (P = 0.88 and P = 0.94). Serum hepcidin:ferritin ratio inversely correlated with homeostasis model assessment of insulin resistance (r = –0.59, P < 0.05).ConclusionInsulin resistance, but not insulin deficiency or hyperglycaemia per se, is associated with inadequate hepcidin levels. Reduced hepcidin concentrations may cause increased body iron stores in insulin-resistant states.

Objective: To investigate the effect of nutrient stimulation of gut hormones by oligofructose supplementation on appetite, energy intake (EI), body weight (BW) and adiposity in overweight and obese volunteers. Methods: In a parallel, single-blind and placebo-controlled study, 22 healthy overweight and obese volunteers were randomly allocated to receive 30 g day 21 oligofructose or cellulose for 6 weeks following a 2-week run-in. Subjective appetite and side effect scores, breath hydrogen, serum short chain fatty acids (SCFAs), plasma gut hormones, glucose and insulin concentrations, EI, BW and adiposity were quantified at baseline and post-supplementation. Results: Oligofructose increased breath hydrogen (P < 0.0001), late acetate concentrations (P 5 0.024), tended to increase total area under the curve (tAUC) 420mins peptide YY (PYY) (P 5 0.056) and reduced tAUC 450mins hunger (P 5 0.034) and motivation to eat (P 5 0.013) when compared with cellulose. However, there was no significant difference between the groups in other parameters although within group analyses showed an increase in glucagon-like peptide 1 (GLP-1) (P 5 0.006) in the cellulose group and a decrease in EI during ad libitum meal in both groups. Conclusions: Oligofructose increased plasma PYY concentrations and suppressed appetite, while cellulose increased GLP-1 concentrations. EI decreased in both groups. However, these positive effects did not translate into changes in BW or adiposity.

The effect of adenosine in insulin secretion and adenylate cyclase activity of rat islets of Langerhans was investigated. Adenosine inhibited insulin secretion stimulated by glucose, glucagon, prostaglandin E2, tolbutamine and theophylline. Adenosine decreased basal adenylate cyclase activity of the islets as well as that stimulated by glucagon, prostaglandin E2 and GTP, although fluoride-stimulated activity was not affected. Neither insulin secretion nor adenylate cyclase activity of the islets was affected by adenine, AMP or ADP. The inhibitory effect of adenosine on adenylate cyclase activity was not altered by either phenoxybenzamine (ac-adrenergic blocker) or propranolol (fi-adrenergic blocker), suggesting that the effect is not mediated through the adrenergic receptors of the islet cells. These results suggest that the intracellular concentration of adenosine in the fl-cell may play a role in regulating insulin secretion and that this effect may be mediated via alterations in the activity of adenylate cyclase in the fl-cell.

Most chronic diseases have been demonstrated to have a link to nutrition. Within food and nutritional research there is a major driver to understand the relationship between diet and disease in order to improve health of individuals. However, the lack of accurate dietary intake assessment in free-living populations, makes accurate estimation of how diet is associated with disease risk difficulty. Thus, there is a pressing need to find solutions to the inaccuracy of dietary reporting. Metabolic profiling of urine or plasma can provide an unbiased approach to characterizing dietary intake and various high-throughput analytical platforms have been used in order to implement targeted and nontargeted assays in nutritional clinical trials and nutritional epidemiology studies. This review describes first the challenges presented in interpreting the relationship between diet and health within individual and epidemiological frameworks. Second, we aim to explore how metabonomics can benefit different types of nutritional studies and discuss the critical importance of selecting appropriate analytical techniques in these studies. Third, we propose a strategy capable of providing accurate assessment of food intake within an epidemiological framework in order establish accurate associations between diet and health.

Context and objective:No current biomarker can reliably predict visceral and liver fat content, both of which are risk factors for cardiovascular disease. Vagal tone has been suggested to influence regional fat deposition. Pancreatic polypeptide (PP) is secreted from the endocrine pancreas under vagal control. We investigated the utility of PP in predicting visceral and liver fat.Patients and Methods:Fasting plasma PP concentrations were measured in 104 overweight and obese subjects (46 men and 58 women). In the same subjects, total and regional adipose tissue, including total visceral adipose tissue (VAT) and total subcutaneous adipose tissue (TSAT), were measured using whole-body magnetic resonance imaging. Intrahepatocellular lipid content (IHCL) was quantified by proton magnetic resonance spectroscopy.Results:Fasting plasma PP concentrations positively and significantly correlated with both VAT (r = 0.57, P < .001) and IHCL (r = 0.51, P < .001), but not with TSAT (r = 0.02, P = .88). Fasting PP concentrations independently predicted VAT after controlling for age and sex. Fasting PP concentrations independently predicted IHCL after controlling for age, sex, body mass index (BMI), waist-to-hip ratio, homeostatic model assessment 2-insulin resistance, (HOMA2-IR) and serum concentrations of triglyceride (TG), total cholesterol (TC), and alanine aminotransferase (ALT). Fasting PP concentrations were associated with serum ALT, TG, TC, low- and high-density lipoprotein cholesterol, and blood pressure (P < .05). These associations were mediated by IHCL and/or VAT. Fasting PP and HOMA2-IR were independently significantly associated with hepatic steatosis (P < .01).Conclusions:Pancreatic polypeptide is a novel predictor of visceral and liver fat content, and thus a potential biomarker for cardiovascular risk stratification and targeted treatment of patients with ectopic fat deposition.

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Supplementing the diet with fermentable carbohydrate (FC) has been suggested to reduce appetite and body weight. Recent findings have demonstrated that inulin-type fructans reduce food intake, body weight and fat mass in rodents (1,2) . However, the effects in humans are inconclusive. This study investigated the effects of FC [oligofructose (OFS)] on appetite profiles, satiety hormone concentration, colonic fermentation, energy intake and body weight following 8 weeks supplementation in overweight and obese adults.22 healthy subjects, male (n 6), female (n 16), mean age 30 (SD 8) years with mean BMI 31.1 (SD 3.4) kg/m 2 completed a randomised, double-blind, parallel study comprised of a 2 week run-in period followed by 30 g fibre/day supplementation of either OFS (n 12) or placebo (cellulose + maltodextrin) (n 10) for 6 weeks. On day 0 (baseline) and day 56 (post-supplementation) subjects were served a standardised breakfast and lunch. Throughout a 420 min postprandial period blood samples were taken to determine peptide YY (PYY) concentrations and visual analogue scales were used to assess subjective appetite feelings. Breath hydrogen was also recorded as a marker of colonic fermentation. Following 420 min participants were served an ad libitum meal to measure energy intake.Dietary supplementation with OFS significantly decreased hunger (P = 0.016), motivation to eat (P = 0.027) and significantly increased breath hydrogen (P = 0.017) on day 56 compared with cellulose treatment. However, subjective fullness (P = 0.187), energy intake (P = 0.344) and PYY (P = 0.145) were not affected by OFS treatment. Supplementing the diet with OFS had no effect on body weight compared with cellulose (P = 0.461) Previous studies that have reported a positive effect of OFS on energy intake and body weight have used a digestible carbohydrate (maltodextrin) as a control (3,4,5) . To our knowledge, this is the first study to compare the effects of OFS on appetite regulation with a nondigestible carbohydrate. In conclusion, supplementing 30 g/day OFS into the diet reduces subjective appetite and increases breath hydrogen. However, there was no significant effect on PYY release, energy intake and body weight compared to cellulose.